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VulnerabilityPublished Updated

CVE-2026-15396: IBM WebSphere Application Server · HTTP Request/Response Smuggling

Affects IBM WebSphere Application ServerSource CVE Database V5

0

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
IBMWebSphere Application ServerAffected
  • =9.0
  • =8.5
Fixed in–
IBMWebSphere Application Server - LibertyAffected
  • >=17.0.0.3 <=26.0.0.5
Fixed in–
Mavencom.ibm.websphere/websphere-application-serverpkg:maven/com.ibm.websphere/websphere-application-serverOther threatsAffected
  • =8.5
  • =9.0
Fixed in–

CPE configurations (6)

  • cpe:2.3:a:ibm:websphere_application_server:9.0:*:*:*:*:*:*:*
  • cpe:2.3:a:ibm:websphere_application_server:9.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:ibm:websphere_application_server:8.5:*:*:*:*:*:*:*
  • cpe:2.3:a:ibm:websphere_application_server:8.5.0:*:*:*:*:*:*:*
  • cpe:2.3:a:ibm:websphere_application_server_liberty:17.0.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:ibm:websphere_application_server_liberty:26.0.0.8:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until an official fix is available, consider monitoring for unusual HTTP transfer-encoding headers and applying any recommended temporary mitigations from IBM. Avoid relying solely on web application firewalls for protection against this vulnerability.

Description

IBM WebSphere Application Server versions 8.5, 9.0, and Liberty 17.0.0.3 through 26.0.0.5 are affected by an HTTP request smuggling vulnerability. This issue arises from improper parsing of the HTTP transfer-encoding request header. Exploitation could allow attackers to poison web caches, bypass web application firewalls, and conduct cross-site scripting (XSS) attacks. The vulnerability has a medium severity with a CVSS score of 6.5.

References

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